DONETSK, UKRAINE (AFP) - Voters in rebel-held eastern Ukraine on Sunday (Nov 11) elected new leaders after the assassination of a top separatist as Kiev urged the West to slap new sanctions on Russia.

In the Donetsk and Lugansk "People's Republics" in Ukraine's industrial east, voters headed to polling stations amid tightened security, with gun-toting, camouflage-clad soldiers deployed to ensure order.

Campaign posters around the Donetsk rebel stronghold called on people to vote "with Russia in your heart".

Washington and Brussels have asked Russia not to hold what they call "illegal" polls, saying that they will further hamper efforts to end a conflict that has killed more than 10,000 people since 2014.

The US embassy in Ukraine said the "sham elections will benefit only Russian proxies in eastern Ukraine, not the Ukrainian people".

But Moscow says the elections are necessary to fill a power vacuum after top rebel Alexander Zakharchenko was killed in a bombing at a Donetsk cafe in August.

Ukrainian President Petro Poroshenko told residents of eastern Ukraine to snub the vote.

"Do not participate in fake elections!" he said late on Saturday, claiming separatist leaders were Russian-controlled puppets.

The Ukrainian foreign ministry on Sunday urged the West to slap new sanctions against Moscow.

"We are calling on the international community to ramp up political and economic pressure on the Kremlin," the ministry said.

The heads of the rebel regions rejected Kiev's criticism.

"It's a free country, we live according to our laws," said Mr Leonid Pasechnik, the 48-year-old acting leader of the republic of Lugansk, after casting his vote.

The acting head of the Donetsk republic, Mr Denis Pushilin, a 37-year-old former operator of a notorious Russian Ponzi scheme, urged people to vote en masse.

"We are choosing our future," said the former negotiator with Kiev who succeeded Mr Zakharchenko.

While several candidates are running in each of the two regions, Mr Pushilin and Mr Pasechnik - both of whom have promised to seek tighter ties with Moscow - were expected to sail to victory.

"I came here to take part in the fate of the republic," said Ms Valentina Slipenko, 77, adding that she voted for Mr Pushilin.

She said she was not bothered by Western threats not to recognise the results of the polls which will also see lawmakers elected.

The last separatist elections were held in 2014 despite protests from the West and Kiev, which did not recognise their results.

Local authorities pulled out all the stops to encourage a high turnout, offering voters discount food and lottery tickets.

Local authorities said 18 per cent of eligible voters had cast their ballots as of 0700 GMT (3pm Singapore time) in both regions. Polling stations were to close at 1700 GMT.

In 2014, Russia annexed Crimea and supported the outbreak of an insurgency in eastern Ukraine in what Kiev sees as punishment for its pivot to the West.

While heavy fighting is over, the conflict regularly claims the lives of soldiers and civilians. Four Ukrainian soldiers have died over the past two days, the military said on Saturday.

Peace negotiations have reached deadlock and Western-backed accords agreed in 2015 are largely moribund.

Many analysts say the polls are a way for Moscow to strengthen its grip on around 3 per cent of Ukrainian territory where 3.7 million people live.

Some locals said their opinions did not matter.

"Two global masters - the United States and Russia - are dividing territories," said Mr Yury, a 50-year-old Donetsk resident, declining to reveal his surname. "Hope has died, as they say."

Some pro-Kiev residents said they would not vote. "The man who was involved in Ponzi schemes has been chosen to be our president," said 34-year-old Tatyana, refusing to give her last name for fear of reprisals. "I am not going to vote."

Kiev's Western backers say that in order to settle the bloodiest European conflict since the Balkans in the 1990s, Russia should withdraw troops from eastern Ukraine and agree to a United Nations peacekeeping mission there.

The Kremlin has denied funnelling troops and arms across the border.